Lawrence Meyers: There are many great things about ETFs, and that includes the ability to see whether money is flowing in or out of them, just like you can with mutual funds. By tracking inflows and outflows, you can gauge market sentiment, particularly if one sector suddenly sees a huge spike.

Because its an ETF as opposed to just a single stock, the sentiment angle has value. One never knows why people are buying or selling a single given stock, but an entire sector, or a given investment arena represented by an ETF can tell you a lot. It may not even relate to the overall market, but to specific areas that are overbought or oversold.

I’m seeing inflows into these three ETFs, and I think the influx of investment dollars into each tells us something about both the sectors they represent and the overall market. So pay close attention.

ProShares UltraShort 20+ Year Treasury (NYSE:TBT) is an ETF that not only shorts long-term Treasury bonds, it’s a leveraged ETF that aims to return twice the Barclays US 20+ Year Treasury Bond Index.

It is particularly interesting to see inflows here, given that the security is down 23% YTD and 16% over the past year. The play here seems to reflect sentiment related to the Fed’s tapering of bond purchases. In theory, if the Fed continues to back off its bond purchases, then bonds will have less support to hold prices up, and thus, prices will drop.

Because the ETF is down YTD, that theory has yet to come to pass. Perhaps the influx of cash suggests that the expected decline in bond prices is around the corner.

iShares International Select Dividend (NYSE:IDV) tracks the Dow Jones EPAC Select Dividend Index, which invests in non-US equities that pay high dividends. It’s a broadly diversified index, up 8.6% YTD, that yields 4%. About a third of its holdings are in UK and Aussie stocks, the latter of which are undervalued and paid out over $40 billion in dividends in 2013. That was double the amount in 2012.

The smart money seems to be moving here as US stocks get stretched. The perception that foreign markets are cheap, particularly Australia, is likely some of the reason for the move. Investors are also likely seeking more diversified exposure, venturing into developed nations so as not to get stuck if the US market corrects.

Consistent with the fear of an overbought market, there’s been an influx of cash into the iShares US Utilities (NYSE:IDU) ETF. This is a straight-up play on a basket of US-based utility stocks.